Fig 5 - uploaded by Simon Potier
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Visual field of Harris's hawks and black kites with the eye at rest. Two views of the visual field of Harris's hawks (N=6; A,C) and black kites (N=3; B,D). (A,B) Orthographic projection of the boundaries of the retinal fields of the two eyes. A latitude and longitude coordinate system was used with the equator aligned vertically in the median sagittal plane. The bird's head is imagined to be at the centre of the globe (grid is at 20 deg intervals in latitude and 10 deg in longitude). (C,D) Horizontal sections trough the horizontal plane (90-270 deg) showing the visual field configuration of each species. Each chart represents the average retinal visual field when the eyes were at rest.
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Animals evolve constrained by their surrounding environment, which shapes their responses to external inputs indirectly by selecting those behaviours that benefit to fitness. In one sentence, animals interact with their environment, and the ability of interfacing with the environment is mainly dependent upon their sensory capacities. These are some...
Citations
... However, it has also shown large knowledge gaps, some of which could potentially be filled by behavioural experiments, specifically using captive, tame and trained birds in falconries (e.g. [122]), and non-invasive techniques such as OCT ( Fig. 5; [46,59,123]), imaging with adaptive optics, and ultrasound. ...
Raptors have always fascinated mankind, owls for their highly sensitive vision, and eagles for their high visual acuity. We summarize what is presently known about the eyes as well as the visual abilities of these birds, and point out knowledge gaps. We discuss visual fields, eye movements, accommodation, ocular media transmittance, spectral sensitivity, retinal anatomy and what is known about visual pathways. The specific adaptations of owls to dim-light vision include large corneal diameters compared to axial (and focal) length, a rod-dominated retina and low spatial and temporal resolution of vision. Adaptations of diurnal raptors to high acuity vision in bright light include rod- and double cone-free foveae, high cone and retinal ganglion cell densities and high temporal resolution. We point out that more studies, preferably using behavioural and non-invasive methods, are desirable.
... It is well accepted that flicker of artificial lights used in their enclosures can be detected by captive birds (Greenwood et al., 2004) and may affect their behaviour, such as mate choice (Evans et al., 2006), induce physiological stress (Maddocks et al., 2001;Evans et al., 2012) and potentially have an impact on visual performance, as shown in mice (Yu et al., 2011). In many countries, raptors are kept for purposes such as falconry or display, which can be essential for raptor conservation and research (Kenward, 2009;Potier, 2016). While most raptors are kept in outdoor aviaries, indoor aviaries using artificial lighting are also used for reproduction (Nelson, 1972). ...
Birds, and especially raptors, are highly visual animals. Some of them have the highest spatial resolving power known in the animal kingdom, allowing prey detection at distance. While many raptors visually track fast-moving and manoeuvrable prey, requiring high temporal resolution, this aspect of their visual system has never been studied before. In this study, we estimated how fast raptors can see, by measuring the flicker fusion frequency of three species with different lifestyles. We found that flicker fusion frequency differed among species, being at least 129 Hz in the peregrine falcon Falco peregrinus, 102 Hz in the saker falcon Falco cherrug and 81 Hz in the Harris's hawk Parabuteo unicinctus We suggest a potential link between fast vision and hunting strategy, with high temporal resolution in the fast-flying falcons that chase fast-moving, manoeuvrable prey and a lower resolution in the Harris's hawk, which flies more slowly and targets slower prey.
Afin de comprendre l'impact des parcs éoliens sur les comportements des grands rapaces et les risques de collision, l'association BECOT coordonne un suivi télémétrique par balises GPS déployées sur les aigles royaux Aquila chrysaetos du sud du massif central. Un mâle adulte territorial est équipé d'une balise GPS depuis février 2014 dans le département de l'Hérault. Le jeune né en 2016 sur ce même territoire a également été équipé, de même que d'autres aigles qui sont amenés à fréquenter cette zone géographique. La période 2014-2015 nous a permis de faire un état initial (seul un parc existait en 2014) avant les premières constructions des nouveaux parcs à l'automne 2015. Depuis 2016, 3 nouveaux parcs éoliens sont désormais construits au coeur du domaine vital concerné. Le suivi télémétrique permet de documenter une importante modification du coeur du domaine vital des aigles royaux territoriaux, qui présente après constructions des premiers parcs une fragmentation importante comparé à la situation avant constructions. Nos analyses mettent en évidence que plus de 450 ha ont été impactés au centre de leur territoire par la construction de deux parcs éoliens, alors que les suivis pré-implantation fournis par les porteurs de projets annonçaient une absence d'impact. Par ailleurs, nos suivis permettent de documenter le premier cas de mortalité en France d'un aigle royal immature suite à une collision avec une éolienne, pourtant équipée d'un système d'effarouchement automatique. Les conséquences des parcs éoliens sont donc particulièrement lourdes pour l'aigle royal sur ce territoire En utilisant les trajectoires de vol enregistrées en 3D à haute résolution, une analyse statistique poussée a permis de quantifier les risques de collision chez les aigles, défini comme étant le temps passé en vol à la hauteur des turbines (entre 60 et 150 m). Le risque de collision est élevé (30-45 %) pour l'aigle royal, quel que soient les conditions aérologiques.